"When you can measure what you are speaking about and express it in numbers, you know something about it" - Lord Kelvin ( 1824 - 1907 )

§ Listen to short excerpt "What is matter?", by Erwin Schrödinger, 1952 :

"We no longer contrast matter with forces and field of force as different entities, we know now that these concepts have to be merged. It is true, we call a spatial region free of matter, call it empty if there is nothing but a gravitational field. But space is never really empty because even far away in the universe there is starlight, and that is matter [ ... ]"

source: Erwin Schrödinger, 1952
Audio - document from the lecture "Was ist Materie?"
English translation: taken from the lecture "Our Conception of Matter" given in 1952 organized by Rencontres Internationales de Genève, Geneva, Switzerland

§ de Broglie's Quantum Equation:

Examples of Determining de Broglie's Wavelength∗

Problem 1: Find the de Broglie wavelength of a wave - particle whose total energy,

is .

Solution:

Problem 2: Find the de Broglie wavelength of earth whose rest or proper mass is .

Solution:

∗

note: some of these examples are used in the future upcoming Relativity Physics and Science Calculator Mac application for de Broglie's quantum equations.

§ References:

"Recherches Sur la Théorie des Quanta" ( Research on the Theory of the Quanta ), par M. Louis de Broglie, Annales de Physique, 10e Série, Tomé III, Janvier - Février, 1925, pgs 21 - 128, the original French version of de Broglie's original 1925 Phd. thesis